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Kubernetes Lab on Baremetal

In “Deploy Your Own Kubernetes Lab” I covered multiple deployment options for a Kubernetes lab, ranging from more lightweight (like running Kubernetes locally) to more realistic ones (like deploying a multi-node cluster) suitable for security research.

In this blog post, I’m going to detail the steps I took to deploy my own Kubernetes Lab on baremetal, and on an Intel NUC in particular.


The Hardware

I was looking for a self-contained option, which - most importantly - didn’t take up much space, so I ended up settling on an Intel NUC, starting with 250GB of storage and 32GB of RAM.

It might be worth noting that, for the initial setup phase, it is also useful to have a small keyboard (like this one) and a monitor (a 7inch one is just fine) around.

At a high level, my home network diagram looks like the one below:

High Level Network Setup.
High Level Network Setup.

Install CoreOS

As the title of this post implies, the aim was to have a Kubernetes cluster running directly on baremetal, hence deciding which operating system to rely on was almost straightforward: Fedora CoreOS (FCOS) is a minimal operating system specifically designed for running containerized workloads securely and at scale.

Let’s see how to get it running on the Intel NUC.

Prepare a Bootable USB

First step in the installation process involves burning a Fedora CoreOS ISO onto a bootable USB stick.

The latest stable version of the ISO for baremetal installations can be found directly on the Fedora website (33.20210301.3.1 at the time of writing). From there, it is simply a matter of burning the ISO, which, on macOS, can be done using tools like Etcher. Once launched, select the CoreOS ISO and the USB device to use, and Etcher will take care of creating a bootable USB from it.

Using Etcher to Create a Bootable USB Stick.
Using Etcher to Create a Bootable USB Stick.

Prepare an Ignition Config

For those new to FCOS (me included before creating this lab), it might be worth explaining what an Ignition file actually is. An Ignition file specifies the configuration for provisioning FCOS instances: the process begins with a YAML configuration file, which gets translated by the FCOS Configuration Transpiler (fcct) into a machine-friendly JSON, which is the final configuration file for Ignition. FCOS ingests the Ignition file only on first boot, applying the whole configuration or failing to boot in case of errors.

The Fedora documentation proved to be excellent in detailing how to create a basic Ignition file that modifies the default FCOS user (named core) to allow logins with an SSH key.

First, on your workstation create a file (named config.fcc) with the following content, and make sure to replace the line starting with ssh-rsa with the contents of your SSH public key file:

➜ cat config.fcc
variant: fcos
version: 1.3.0
passwd:
  users:
    - name: core
      groups:
        - docker
        - wheel
        - sudo
      ssh_authorized_keys:
        - ssh-rsa AAAA...

In the config above, we are basically telling FCOS to add the default user named core to three additional groups (docker, wheel, and sudo), as well as to allow key based authentication with the the public SSH key specified in the ssh_authorized_keys section. The public key will be provisioned to FCOS machine via Ignition, whereas the private counterpart needs to be available to your user on your local workstation, in order to remotely authenticate over SSH.

Next, we need to use fcct, the Fedora CoreOS Config Transpiler, to produces a JSON Ignition file from a YAML FCC file. An easy way to use fcct is to run it in a container:

➜ docker run --rm -i quay.io/coreos/fcct:release --pretty --strict < config.fcc > config.ign
➜ cat config.ign
{
  "ignition": {
    "version": "3.2.0"
  },
  "passwd": {
    "users": [
      {
        "groups": [
          "docker",
          "wheel",
          "sudo"
        ],
        "name": "core",
        "sshAuthorizedKeys": [
          "ssh-rsa AAAA..."
        ]
      }
    ]
  }
}

Since this config.ign will be needed to boot FCOS, we need to make it temporarily available for devices on the local network. There are multiple ways to accomplish this: I did opt to quickly spin up updog (a replacement for Python’s SimpleHTTPServer):

Sharing the Ignition File over LAN.
Sharing the Ignition File over LAN.

Install from Live USB

With the Ignition config ready, plug the USB stick in the Intel NUC, turn it on, and make sure to select that media as preferred boot option. If the ISO has been burnt correctly, you should end up in a shell as the core user.

The actual installation can be accomplished in a quite straightforward way with coreos-installer:

$ sudo coreos-installer install /dev/sda \
        --insecure-ignition --ignition-url http://192.168.1.150/config.ign

The command above instructs coreos-installer to use the Ignition config we are making available to local network from our workstation (192.168.1.150 in my case). The --insecure-ignition flag is needed if the Ignition file is served over plaintext HTTP rather than TLS.

After a reboot of the Intel NUC, you should be able to SSH into it from your workstation:

❯ ssh [email protected]
Fedora CoreOS 33.20210217.3.0
Tracker: https://github.com/coreos/fedora-coreos-tracker
Discuss: https://discussion.fedoraproject.org/c/server/coreos/

[[email protected] ~]$ id
uid=1000(core) gid=1000(core) groups=1000(core),4(adm),10(wheel),16(sudo),190(systemd-journal)

And that’s it! FCOS is now up and running. Next step is installing Kubernetes on it.


Install Kubernetes

The installation process for Kubernetes is a bit more lenghty, and can be broken up in a few sections: installation of dependencies, installation of the cluster, and network setup.

Install Dependencies

While looking around (i.e., Googling) for the most effective way to deploy a vanilla Kubernets on FCOS I came across a really detailed article from Matthias Preu (Fedora CoreOS - Basic Kubernetes Setup) describing exactly this process. Note that the remainder of this sub-section has been based heavily on Matthias’ setup, and you should refer to his blog post for a detailed explanation of each installation step.

First, setup CRI-O as the container runtime:

# Activating Fedora module repositories
$ sed -i -z s/enabled=0/enabled=1/ /etc/yum.repos.d/fedora-modular.repo
$ sed -i -z s/enabled=0/enabled=1/ /etc/yum.repos.d/fedora-updates-modular.repo
$ sed -i -z s/enabled=0/enabled=1/ /etc/yum.repos.d/fedora-updates-testing-modular.repo

# Setting up the CRI-O module
$ mkdir /etc/dnf/modules.d
$ cat <<EOF > /etc/dnf/modules.d/cri-o.module
[cri-o]
name=cri-o
stream=1.17
profiles=
state=enabled
EOF

# Installing CRI-O
$ rpm-ostree install cri-o
$ systemctl reboot

$ modprobe overlay && modprobe br_netfilter
$ cat <<EOF > /etc/modules-load.d/crio-net.conf
overlay
br_netfilter
EOF

$ cat <<EOF > /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

$ sysctl --system
$ sed -i -z s+/usr/share/containers/oci/hooks.d+/etc/containers/oci/hooks.d+ /etc/crio/crio.conf

Next, install all tooling required to manage the cluster (kubeadm, kubelet and kubectl):

$ cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
EOF

$ rpm-ostree install kubelet kubeadm kubectl
$ systemctl reboot

$ setenforce 0
$ sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

$ systemctl enable --now cri-o && systemctl enable --now kubelet
$ echo "KUBELET_EXTRA_ARGS=--cgroup-driver=systemd" | tee /etc/sysconfig/kubelet

Install the Cluster

Before starting the installation of the cluster itself, a custom cluster configuration needs to be created:

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[[email protected] core]$ cat <<EOF > clusterconfig.yml
apiVersion: kubeadm.k8s.io/v1beta2
kind: ClusterConfiguration
kubernetesVersion: v1.20.5
controllerManager:
  extraArgs:
    flex-volume-plugin-dir: "/etc/kubernetes/kubelet-plugins/volume/exec"
networking:
  podSubnet: 10.244.0.0/16
---
apiVersion: kubeadm.k8s.io/v1beta2
kind: InitConfiguration
nodeRegistration:
  criSocket: /var/run/crio/crio.sock
EOF
  • Line 4: the Kubernetes version to deploy (1.20.5 in my case).
  • Line 9: the subnet to be used to allocate pods’ IP addresses. Pay attention that the prefix 10.244.X.X/X is required by Flannel (the chosen networking solution) when used in conjunction with kubeadm.

With the config ready, we can use kubeadm to install the cluster:

[[email protected] core]$ kubeadm init --config clusterconfig.yml

[init] Using Kubernetes version: v1.20.5
[preflight] Running pre-flight checks
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [cluster kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.1.151]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [cluster localhost] and IPs [192.168.1.151 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [cluster localhost] and IPs [192.168.1.151 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 70.502118 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.20" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node cluster as control-plane by adding the labels "node-role.kubernetes.io/master=''" and "node-role.kubernetes.io/control-plane='' (deprecated)"
[mark-control-plane] Marking the node cluster as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 9fcige.wjsr2lub81pr86tc
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.151:6443 --token <redacted> \
    --discovery-token-ca-cert-hash sha256:<redacted>

As it can be seen from the output of kubeadm itself, we can now grant the core user (or any local user, actually) access to the cluster by copying the kubeconfig file to its .kube directory:

[[email protected] ~]$ mkdir -p $HOME/.kube
[[email protected] ~]$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[[email protected] ~]$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

The same config can also be copied (e.g., via scp) onto your workstation, so to interact with the cluster remotely without having to SSH into the NUC:

➜ kubectx cluster  # alias for the cluster
➜ k cluster-info
+ kubectl cluster-info
Kubernetes control plane is running at https://192.168.1.151:6443
KubeDNS is running at https://192.168.1.151:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

➜ kg nodes -o wide
+ kubectl get nodes -o wide
NAME      STATUS   ROLES                  AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                        KERNEL-VERSION            CONTAINER-RUNTIME
cluster   Ready    control-plane,master   60m   v1.20.5   192.168.1.151   <none>        Fedora CoreOS 33.20210301.3.1   5.10.19-200.fc33.x86_64   cri-o://1.19.1

From the output above you can see how the control plane is reachable at the NUC’s local IP address (192.168.1.151 in my case).

Network Setup

Although it might seem everything is setup, there are still a couple of steps missing.

First, since I only have one node available, it is necessary to allow the master node itself to schedule pods. This is done by removing a taint:

➜ k taint nodes --all node-role.kubernetes.io/master-

Second, we need to deploy a networking solution like Flannel:

[[email protected] ~]$ sudo sysctl net.bridge.bridge-nf-call-iptables=1
[[email protected] ~]$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

After this, you should have all the necessary components for a basic Kubernetes cluster up and running:

➜ kgpo --all-namespaces
+ kubectl get pods --all-namespaces
NAMESPACE            NAME                                        READY   STATUS      RESTARTS   AGE
kube-system          coredns-74ff55c5b-2qdkf                     1/1     Running     0          3d17h
kube-system          coredns-74ff55c5b-5blfn                     1/1     Running     0          3d17h
kube-system          etcd-cluster                                1/1     Running     0          3d17h
kube-system          kube-apiserver-cluster                      1/1     Running     0          3d17h
kube-system          kube-controller-manager-cluster             1/1     Running     0          3d17h
kube-system          kube-flannel-ds-22ltx                       1/1     Running     0          3d17h
kube-system          kube-proxy-2lbvn                            1/1     Running     0          3d17h
kube-system          kube-scheduler-cluster                      1/1     Running     0          3d17h

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Ingress Controllers and LoadBalancing on Baremetal

We now have a fully functional cluster running on baremetal, but at some point you will have to expose some services. This is often accomplished with an NGINX Ingress Controller (source), an Ingress controller which uses NGINX as a reverse proxy and load balancer.

Unlike clusters running in the cloud, where network load balancers are available on-demand and can be configured simply via Kubernetes manifests, baremetal clusters require a slightly different setup to offer the same kind of access to external clients.

Cloud vs Baremetal Environments - Courtesy of NGINX Ingress Controller.
Cloud vs Baremetal Environments - Courtesy of NGINX Ingress Controller.

Install NGINX Controller

First of all, let’s deploy the NGINX Ingress Controller:

➜ kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.44.0/deploy/static/provider/baremetal/deploy.yaml
namespace/ingress-nginx created
serviceaccount/ingress-nginx created
configmap/ingress-nginx-controller created
clusterrole.rbac.authorization.k8s.io/ingress-nginx unchanged
clusterrolebinding.rbac.authorization.k8s.io/ingress-nginx unchanged
role.rbac.authorization.k8s.io/ingress-nginx created
rolebinding.rbac.authorization.k8s.io/ingress-nginx created
service/ingress-nginx-controller-admission created
service/ingress-nginx-controller created
deployment.apps/ingress-nginx-controller created
validatingwebhookconfiguration.admissionregistration.k8s.io/ingress-nginx-admission configured
serviceaccount/ingress-nginx-admission created
clusterrole.rbac.authorization.k8s.io/ingress-nginx-admission unchanged
clusterrolebinding.rbac.authorization.k8s.io/ingress-nginx-admission unchanged
role.rbac.authorization.k8s.io/ingress-nginx-admission created
rolebinding.rbac.authorization.k8s.io/ingress-nginx-admission created
job.batch/ingress-nginx-admission-create created
job.batch/ingress-nginx-admission-patch created

After a few seconds, we should be able to see that the Ingress Controller pods have started in the ingress-nginx namespace:

➜ kubectl get pods -n ingress-nginx \
                   -l app.kubernetes.io/name=ingress-nginx --watch
+ kubectl get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx --watch
NAME                                        READY   STATUS      RESTARTS   AGE
ingress-nginx-admission-create-ppzs6        0/1     Completed   0          48s
ingress-nginx-admission-patch-x86wg         0/1     Completed   1          48s
ingress-nginx-controller-67897c9494-bht6p   1/1     Running     0          48s

Install MetalLB

As per NGINX’s documentation, MetalLB provides a network load-balancer implementation for Kubernetes clusters that do not run on a supported cloud provider, effectively allowing the usage of LoadBalancer Services within any cluster.

MetalLB for Baremetal Environments - Courtesy of NGINX Ingress Controller.
MetalLB for Baremetal Environments - Courtesy of NGINX Ingress Controller.

MetalLB can be installed by applying a couple of manifests:

# Enable Strict ARP mode
➜ kubectl get configmap kube-proxy -n kube-system -o yaml  | \
              sed -e "s/strictARP: false/strictARP: true/" | \
              kubectl apply -f - -n kube-system

# Create namespace
➜ kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.5/manifests/namespace.yaml
namespace/metallb-system created

# Deploy
➜ kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.5/manifests/metallb.yaml
podsecuritypolicy.policy/controller configured
podsecuritypolicy.policy/speaker configured
serviceaccount/controller created
serviceaccount/speaker created
clusterrole.rbac.authorization.k8s.io/metallb-system:controller unchanged
clusterrole.rbac.authorization.k8s.io/metallb-system:speaker unchanged
role.rbac.authorization.k8s.io/config-watcher created
role.rbac.authorization.k8s.io/pod-lister created
clusterrolebinding.rbac.authorization.k8s.io/metallb-system:controller unchanged
clusterrolebinding.rbac.authorization.k8s.io/metallb-system:speaker unchanged
rolebinding.rbac.authorization.k8s.io/config-watcher created
rolebinding.rbac.authorization.k8s.io/pod-lister created
daemonset.apps/speaker created
deployment.apps/controller created

# Create secret (on first install only)
➜ kubectl create secret generic -n metallb-system memberlist --from-literal=secretkey="$(openssl rand -base64 128)"
secret/memberlist created

This will deploy MetalLB to the cluster, under the metallb-system namespace. The main components are:

  • metallb-system/controller (deployment): the cluster-wide controller that handles IP address assignments.
  • metallb-system/speaker (daemonset): the component that speaks the protocol(s) to make the services reachable.
  • memberlist (secret): which contains the secretkey to encrypt the communication between speakers for the fast dead node detection.
  • Service accounts for the controller and speaker, along with the RBAC permissions that the components need to function.

After a few seconds, we can verify the status of the installation:

➜ kgpo -n metallb-system
+ kubectl get pods -n metallb-system
NAME                          READY   STATUS    RESTARTS   AGE
controller-65db86ddc6-zbqjn   1/1     Running   0          90s
speaker-2brq5                 1/1     Running   0          90s

Altough running, MetalLB’s components will remain idle until they will get provided with a configmap. In this regard, MetalLB requires a dedicated pool of IP addresses in order to be able to take ownership of the ingress-nginx Service. Bear in mind that this pool of IPs must be dedicated to MetalLB’s use, the Kubernetes node IPs or IPs handed out by a DHCP server cannot be reused for this purpose.

➜ cat metallb-config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  namespace: metallb-system
  name: config
data:
  config: |
    address-pools:
    - name: default
      protocol: layer2
      addresses:
      - 192.168.1.160-192.168.1.190
➜ k apply -f metallb-config.yaml
+ kubectl apply -f metallb-config.yaml
configmap/config created

After creating such ConfigMap (for my setup I chose 192.168.1.160-192.168.1.190 as reserved addresses), MetalLB will take ownership of the IP addresses in the pool and will update the External IP field of each Service of type LoadBalancer.

Install HAProxy

Finally, the last component we need is the HAProxy Ingress Controller, which can be used to route traffic from outside the cluster to services within the cluster.

As per documentation, we first need to add the HAProxy Ingress’ Helm repository:

➜ helm repo add haproxy-ingress https://haproxy-ingress.github.io/charts
"haproxy-ingress" has been added to your repositories

Next, we need to create a haproxy-ingress-values.yaml file with custom parameters and use it during the installation with Helm:

cat haproxy-ingress-values.yaml
controller:
  hostNetwork: true

➜ helm install haproxy-ingress haproxy-ingress/haproxy-ingress\
                --create-namespace --namespace haproxy\
                --version 0.12.1\
                -f haproxy-config.yaml
NAME: haproxy-ingress
LAST DEPLOYED: Sat Mar 20 14:56:10 2021
NAMESPACE: haproxy
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
HAProxy Ingress has been installed!

HAProxy is exposed as a `LoadBalancer` type service.
It may take a few minutes for the LoadBalancer IP to be available.
You can watch the status by running:

    kubectl --namespace haproxy get services haproxy-ingress -o wide -w

An example Ingress that makes use of the controller:

  apiVersion: networking.k8s.io/v1beta1
  kind: Ingress
  metadata:
    annotations:
      kubernetes.io/ingress.class: haproxy
    name: example
    namespace: default
  spec:
    rules:
      - host: www.example.com
        http:
          paths:
            - backend:
                serviceName: exampleService
                servicePort: 8080
              path: /

To verify the successful installation of HAProxy:

➜ kubectl --namespace haproxy get services haproxy-ingress -o wide -w
+ kubectl --namespace haproxy get services haproxy-ingress -o wide -w
NAME              TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE   SELECTOR
haproxy-ingress   LoadBalancer   10.100.29.75   192.168.1.160   80:30349/TCP,443:32039/TCP   3m53s   app.kubernetes.io/instance=haproxy-helm,app.kubernetes.io/name=haproxy-ingress

As it can be seen in the output above, MetalLB updated the External IP of the haproxy-ingress Service (which is of type LoadBalancer), and assigned it to one of the reserved IP addresses (192.168.1.160 in this case).

HAProxy Service.
HAProxy Service.

Testing

If you followed along, you should have the following pods currently running in your cluster:

➜ kgpo --all-namespaces
+ kubectl get pods --all-namespaces
NAMESPACE            NAME                                        READY   STATUS      RESTARTS   AGE
haproxy              haproxy-ingress-54c586f8b8-94mbd            1/1     Running     0          3d4h
ingress-nginx        ingress-nginx-admission-create-ppzs6        0/1     Completed   0          3d5h
ingress-nginx        ingress-nginx-admission-patch-x86wg         0/1     Completed   1          3d5h
ingress-nginx        ingress-nginx-controller-67897c9494-bht6p   1/1     Running     0          3d5h
kube-system          coredns-74ff55c5b-2qdkf                     1/1     Running     0          3d21h
kube-system          coredns-74ff55c5b-5blfn                     1/1     Running     0          3d21h
kube-system          etcd-cluster                                1/1     Running     0          3d21h
kube-system          kube-apiserver-cluster                      1/1     Running     0          3d21h
kube-system          kube-controller-manager-cluster             1/1     Running     0          3d21h
kube-system          kube-flannel-ds-22ltx                       1/1     Running     0          3d21h
kube-system          kube-proxy-2lbvn                            1/1     Running     0          3d21h
kube-system          kube-scheduler-cluster                      1/1     Running     0          3d21h
metallb-system       controller-65db86ddc6-zbqjn                 1/1     Running     0          3d5h
metallb-system       speaker-2brq5                               1/1     Running     0          3d5h

Let’s go and try to deploy a Service within the cluster. For this, we can use the “Expose an Application with NGINX Plus Ingress Controller” walkthrough as a starting point:

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➜ cat sample-deployment.yaml
---
apiVersion: v1
kind: Namespace
metadata:
  name: test
---
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: bookinfo-ingress
  annotations:
    kubernetes.io/ingress.class: haproxy
spec:
  rules:
  - host: product.192.168.1.151.nip.io  # IP of the NUC
    http:
      paths:
      - path: /
        backend:
          serviceName: productpage
          servicePort: 9080
---
apiVersion: v1
kind: Service
metadata:
  name: productpage
  namespace: test
  labels:
    app: productpage
    service: productpage
spec:
  type: LoadBalancer
  ports:
  - name: http
    port: 80
    targetPort: 9080
  selector:
    app: productpage
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: bookinfo-productpage
  namespace: test
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: productpage-v1
  namespace: test
  labels:
    app: productpage
    version: v1
spec:
  replicas: 1
  selector:
    matchLabels:
      app: productpage
      version: v1
  template:
    metadata:
      labels:
        app: productpage
        version: v1
    spec:
      serviceAccountName: bookinfo-productpage
      containers:
      - name: productpage
        image: docker.io/istio/examples-bookinfo-productpage-v1:1.15.0
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 9080

Note how in line 16 we had to specify the IP address of the Intel NUC as part of the Ingress’ host. Let’s apply this manifest:

➜ k apply -f sample-deployment.yaml
+ kubectl apply -f sample-deployment.yaml
namespace/test configured
ingress.networking.k8s.io/bookinfo-ingress created
service/productpage created
serviceaccount/bookinfo-productpage created
deployment.apps/productpage-v1 created

➜ kgsvc
+ kubectl get service
NAME          TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
productpage   LoadBalancer   10.106.62.46   192.168.1.161   80:32225/TCP   4s

➜ kging
+ kubectl get ingress
NAME               CLASS    HOSTS                          ADDRESS   PORTS   AGE
bookinfo-ingress   <none>   product.192.168.1.151.nip.io             80      22s

We can see how http://product.192.168.1.151.nip.io is getting exposed via the bookinfo-ingress and will be reachable from clients within the local network:

Sample Deployment Exposed to LAN.
Sample Deployment Exposed to LAN.

Volumes and Stateful Deployments

The last thing I wanted to try was the cluster’s compatibility with volumes and stateful deployments. Luckily, it turned out that the standard setup worked out of the box:

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---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: task-pv-volume
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: '/mnt/data'
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: task-pv-claim
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 3Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: task-pv-pod
spec:
  volumes:
    - name: task-pv-storage
      persistentVolumeClaim:
        claimName: task-pv-claim
  containers:
    - name: task-pv-container
      image: nginx
      ports:
        - containerPort: 80
          name: 'http-server'
      volumeMounts:
        - mountPath: '/usr/share/nginx/html'
          name: task-pv-storage
  • Lines 2-16: create a hostPath PersistentVolume which uses a directory on the Node (the Intel NUC) to emulate network-attached storage.
  • Lines 18-29: create a PersistentVolumeClaim, used by pods to request physical storage.
  • Lines 31-49: create a sample Pod which attaches the task-pv-claim PVC.

Apply the manifest and, after a few moments, the Volume will show as Bound:

+ kubectl get pv
NAME             CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                   STORAGECLASS   REASON   AGE
task-pv-volume   10Gi       RWO            Retain           Bound    default/task-pv-claim   manual                  37s

➜ kg pvc
+ kubectl get pvc
NAME            STATUS   VOLUME           CAPACITY   ACCESS MODES   STORAGECLASS   AGE
task-pv-claim   Bound    task-pv-volume   10Gi       RWO            manual         33s

From here we can quickly test the setup by creating a text file under the /mnt/data directory of the Intel NUC, and then trying to access it from the test pod:

# Create file on the host
[[email protected] data]$ echo "Hello from Kubernetes storage" > /mnt/data/index.html

# Exec on the pod and validate access
➜ kubectl exec -it task-pv-pod -- /bin/bash

[email protected]:/# apt update && apt install curl
[email protected]:/# curl http://localhost/
Hello from Kubernetes storage

Automate the Setup

The setup described in this post has been automated as part of k8s-lab-plz, a modular Kubernetes Lab which provides an easy and streamlined way to deploy a test cluster with support for different components. You can read more about it at: Introducing k8s-lab-plz: A modular Kubernetes Lab.

In particular, you can refer to the Baremetal Setup page of the documentation for specific instructions.


Remotely Access the Cluster

To take the setup a step further, in Remotely Access your Kubernetes Lab with Cloudflare Tunnel I explain how to use Cloudflare Tunnel to connect the Intel NUC to the Cloudflare network, and Auditable Terminal to connect to it remotely using nothing more than a browser.


Conclusions

In this blog post, part of the “Kubernetes Primer for Security Professionals” series, I described the approach took to deploy my own Kubernetes Lab on baremetal, and on an Intel NUC in particular.

I hope you found this post useful and interesting, and I’m keen to get feedback on it! If you find the information shared was useful, if something is missing, or if you have ideas on how to improve it, please let me know on Twitter.

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Marco Lancini

Marco Lancini
Hi, I'm Marco Lancini. I'm a Security Engineer, mainly interested in cloud native technologies and security...  [read more]